You did this because of deep insecurities and wanting others to think highly of you. In the process, you hurt someone else and inadvertently revealed your peer group of the time to be shallow people.

I would suggest the first thing to do is to really look deeply at your motives and what’s behind them. Why did you want their approval? What feelings about yourself were you searching for that prompted you to lie at the expense of another? Ultimately, this will help you understand yourself on a deep level, which will let you forgive yourself. Once you have found this peace, I would reach out again to this person you wronged, let her know the work you’ve done to understand yourself and let her know how remorseful you are about it, should she forgive you or not.

Don’t ever forget that you’re human, and we all succumb to temptations we later regret. You need to cut yourself some slack and forgive yourself. Learn from this and strive to be honest with yourself and others.